1. Field of the Invention
The present invention relates to a motor vehicle brake control system and particularly to a system modification for activating the system when the vehicle is inoperative.
2. Description of the Prior Art
Safety, convenience and operating modules are typical components of a motor vehicle electrical system. The electrical system is powered by the vehicle storage battery, which is charged by the vehicle""s engine driven alternator when the vehicle is operated. This battery has a finite energy capacity and therefore, current drain when the vehicle is inoperative must be limited, so as to provide cranking energy to start the vehicle""s engine following prolonged periods of non-use. When the vehicle operator turns the key in the vehicle ignition switch, an electrical activation signal is sent through the electrical system to activate the vehicle electrical system enabling the safety, convenience and operating modules to be used by the operator.
To power up the vehicle electrical system using the ignition key, the operator must have the ignition key in a specific position. Occasionally, the operator may need to use vehicle functions quickly without having to have the ignition key in the switch or having it turned to a specific position to activate electrical system operating and monitoring features. Therefore, a need exists for a system enabling a vehicle electrical system to be operative without use of the ignition key. This type of feature would be especially beneficial for vehicles which feature an all electrical brake system or an electrical brake booster in which braking hydraulic pressure is boosted through an electromechanical booster unit, which does not require intake manifold vacuum as a pressure source. For such vehicles, it is desirable that the driver would not be required to have the key in a specific position or the engine running to be able to apply enough brake pressure to prevent vehicle motion. While this feature would be beneficial, cost is always a factor. Accordingly, it would be desirable to add an alternative method of activating portions of the vehicle electronics without making a significant impact on the cost of the electrical system.
Alternative methods of activating a vehicle""s electronics other than with a key turned in the ignition switch have been proposed. U.S. Pat. No. 5,945,745, issued Aug. 31, 1999 describes an apparatus for controlling power to a vehicle electrical system when the ignition is off. While this apparatus would activate the electrical system with the ignition switch off, it requires several expensive components to be added to the vehicle electrical system, including a microprocessor.
U.S. Pat. No. 6,037,675, issued Mar. 14, 2000, also discusses a system for activating electrical systems in a vehicle using a method other than turning the key in the ignition switch. In this system, the operator can use a security card or can push a button on a remote unit to activate the vehicle electrical system. However, since this invention utilizes an entirely separate remote control unit, there is also significant additional cost.
From the above discussion, it is clear that the need exists for a system for activating a motor vehicle""s electronics without the need to have an ignition key in a specific position or adding additional expensive components. It is therefore a primary object of this invention to fulfill that need by providing a system which allows operators to activate portions of the vehicle""s electronics which does not require using the vehicle ignition key.
Briefly described, these and other objects are accomplished according to the present invention by providing an electrical circuit having a switch associated with actuation of the service brake pedal, so that when the operator applies force to the brake pedal, even when the ignition key is not in the proper position, power will be applied to the brake system to activate it, thus making its functions available.
Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings.